These drains act like an expressway for pollution and debris in our cities, roads, gutters and gardens, sending a cocktail of contaminants directly into the aquatic ecosystems that lie at the end of the pipe.

A pollution cocktail

Stormwater is a mixture of rain and any dissolved or solid pollutants carried along with it. The excess water flowing along streets and gutters picks up litter, oil and grease, and metals. Run-off from parks and gardens introduces fertilisers, pathogens, pesticides and soil.

You can help at home too by retaining vegetation, installing rainwater tanks, clearing excess leaf litter and debris from guttering and driveways, and reducing the use of pesticides and fertilisers on gardens. Rainwater tanks have proven particularly successful at capturing all stormwater for reuse in toilet flushing and irrigation.

While we need to clean up our waterways, we also need to make sure that enough water and organic matter are flowing through our rivers and into the oceans. Getting the balance right will make for better cities and healthier oceans.

Katherine Dafforn is a Senior Research Associate in Marine Ecology, UNSW.